Cleavage of PKN by caspase-3-like protease.
(A) Inhibition of PKN cleavage during apoptosis
by DEVD-CHO. Jurkat cells were pretreated with various concentrations
of the tetrapeptide inhibitor of caspase-1 (YVAD-CHO) or caspase-3
(DEVD-CHO) for 1 h, as indicated, and then incubated with α-Fas
mAb (150 ng/ml) for an additional 6 h. The cleavage of PKN was
analyzed by immunoblotting with αC6. (B) In
vitro cleavage of PKN by recombinant caspases. His-PKN (40 ng)
was incubated with recombinant His-caspase-3 (Casp-3) or GST-caspase-6
(Casp-6) at 30°C for the indicated time periods, then analyzed by
immunoblotting with PKN (C-19). The cleavage products corresponding to
AF1, AF2, and AF3 were observed from 10-min incubation with caspase-3,
while a cleavage product of a different size was observed from
caspase-6 cleavage. White and black arrowheads on the right of the blot
indicate the proteins uncleaved and cleaved by caspase-3, respectively.
Gray arrowhead indicates a caspase-3 cleavage product that was not
detected in vivo. Molecular mass markers in kDa are
indicated on the left.